Changes in timekeeping.rst

3dc6ffae - timekeeping: Introduce fast accessor to clock tai

Thu, 14 Apr 2022 09:18:03 +0000

timekeeping: Introduce fast accessor to clock taiIntroduce fast/NMI safe accessor to clock tai for tracing. The Linux kerneltracing infrastructure has support for using different clocks to generatetimestamps for trace events. Especially in TSN networks it's useful to have TAIas trace clock, because the application scheduling is done in accordance to thenetwork time, which is based on TAI. With a tai trace_clock in place, it becomesvery convenient to correlate network activity with Linux kernel applicationtraces.Use the same implementation as ktime_get_boot_fast_ns() does by reading themonotonic time and adding the TAI offset. The same limitations as for the fastboot implementation apply. The TAI offset may change at run time e.g., bysetting the time or using adjtimex() with an offset. However, these kind ofoffset changes are rare events. Nevertheless, the user has to be aware and dealwith it in post processing.An alternative approach would be to use the same implementation asktime_get_real_fast_ns() does. However, this requires to add an additional u64member to the tk_read_base struct. This struct together with a seqcount isdesigned to fit into a single cache line on 64 bit architectures. Adding a newmember would violate this constraint.Signed-off-by: Kurt Kanzenbach Signed-off-by: Thomas Gleixner Cc: Steven Rostedt Link: https://lore.kernel.org/r/20220414091805.89667-2-kurt@linutronix.de List of files: /linux-6.15/Documentation/core-api/timekeeping.rst

404e603f - docs: timekeeping: Use correct prototype for deprecated functions

Tue, 14 Apr 2020 22:12:22 +0000

docs: timekeeping: Use correct prototype for deprecated functionsUse the correct prototypes for do_gettimeofday(), getnstimeofday() andgetnstimeofday64(). All of these returned void and passed the returnvalue by reference. This should make the documentation of theirdeprecation and replacements easier to search for.Signed-off-by: Chris Packham Acked-by: Arnd Bergmann Link: https://lore.kernel.org/r/20200414221222.23996-1-chris.packham@alliedtelesis.co.nzSigned-off-by: Jonathan Corbet List of files: /linux-6.15/Documentation/core-api/timekeeping.rst

d48e0cd8 - timekeeping: Boot should be boottime for coarse ns accessor

Mon, 24 Jun 2019 09:15:39 +0000

timekeeping: Boot should be boottime for coarse ns accessorSomewhere in all the patchsets before, this cleanup got lost.Signed-off-by: Jason A. Donenfeld Signed-off-by: Thomas Gleixner Cc: Arnd Bergmann Link: https://lkml.kernel.org/r/20190624091539.13512-1-Jason@zx2c4.com List of files: /linux-6.15/Documentation/core-api/timekeeping.rst

4c54294d - timekeeping: Add missing _ns functions for coarse accessors

Fri, 21 Jun 2019 20:32:49 +0000

timekeeping: Add missing _ns functions for coarse accessorsThis further unifies the accessors for the fast and coarse functions, sothat the same types of functions are available for each. There was alsoa bit of confusion with the documentation, which prior advertised afunction that has never existed. Finally, the vanilla ktime_get_coarse()was omitted from the API originally, so this fills this oversight.Signed-off-by: Jason A. Donenfeld Signed-off-by: Thomas Gleixner Reviewed-by: Arnd Bergmann Link: https://lkml.kernel.org/r/20190621203249.3909-3-Jason@zx2c4.com List of files: /linux-6.15/Documentation/core-api/timekeeping.rst

9285ec4c - timekeeping: Use proper clock specifier names in functions

Fri, 21 Jun 2019 20:32:48 +0000

timekeeping: Use proper clock specifier names in functionsThis makes boot uniformly boottime and tai uniformly clocktai, toaddress the remaining oversights.Signed-off-by: Jason A. Donenfeld Signed-off-by: Thomas Gleixner Reviewed-by: Arnd Bergmann Link: https://lkml.kernel.org/r/20190621203249.3909-2-Jason@zx2c4.com List of files: /linux-6.15/Documentation/core-api/timekeeping.rst

e0cef9ff - Documentation: fix typo CLOCK_MONONOTNIC_COARSE

Fri, 07 Jun 2019 08:07:02 +0000

Documentation: fix typo CLOCK_MONONOTNIC_COARSEFix typo in documentation file timekeeping.rst: CLOCK_MONONOTNIC_COARSEshould be CLOCK_MONOTONIC_COARSE.Signed-off-by: Aurelien Thierry Signed-off-by: Jonathan Corbet List of files: /linux-6.15/Documentation/core-api/timekeeping.rst

0e3fd810 - Documentation: document ktime_get_*() APIs

Tue, 10 Jul 2018 14:46:41 +0000

Documentation: document ktime_get_*() APIsAs Dave Chinner points out, we don't have a proper documentation for thektime_get() family of interfaces, making it rather unclear which of theover 30 (!) interfaces one should actually use in a driver or elsewherein the kernel.I wrote up an explanation from how I personally see the interfaces,documenting what each of the functions do and hopefully making it a bitclearer which should be used where.This is the first time I tried writing .rst format documentation, soin addition to any mistakes in the content, I probably also introducenonstandard formatting ;-)I first tried to add an extra section toDocumentation/timers/timekeeping.txt, but this is currently not includedin the generated API, and it seems useful to have the API docs as partof what gets generated inhttps://www.kernel.org/doc/html/latest/core-api/index.html#core-utilitiesinstead, so I started a new file there.I also considered adding the documentation inline in theinclude/linux/timekeeping.h header, but couldn't figure out how to dothat in a way that would result both in helpful inline comments aswell as readable html output, so I settled for the latter, witha small note pointing to it from the header.Cc: Dave Chinner Cc: John Stultz Cc: Thomas Gleixner Cc: Stephen Boyd Tested-by: Randy Dunlap Reviewed-by: Randy Dunlap Reviewed-by: Linus Walleij Signed-off-by: Arnd Bergmann Signed-off-by: Jonathan Corbet List of files: /linux-6.15/Documentation/core-api/timekeeping.rst